[libc-commits] [libc] first trailing zero (PR #81526)
via libc-commits
libc-commits at lists.llvm.org
Mon Feb 12 12:28:17 PST 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-libc
Author: Nick Desaulniers (nickdesaulniers)
<details>
<summary>Changes</summary>
- [libc][stdbit] implement stdc_first_leading_one (C23)
- add tg macros to doc
- [libc][stdbit] implement stdc_first_trailing_zero (C23)
---
Patch is 44.95 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/81526.diff
39 Files Affected:
- (modified) libc/config/linux/x86_64/entrypoints.txt (+10)
- (modified) libc/docs/stdbit.rst (+30-30)
- (modified) libc/include/llvm-libc-macros/stdbit-macros.h (+44)
- (modified) libc/spec/stdc.td (+14-2)
- (modified) libc/src/__support/CPP/bit.h (+59)
- (modified) libc/src/stdbit/CMakeLists.txt (+2)
- (added) libc/src/stdbit/stdc_first_leading_one_uc.cpp (+20)
- (added) libc/src/stdbit/stdc_first_leading_one_uc.h (+18)
- (added) libc/src/stdbit/stdc_first_leading_one_ui.cpp (+20)
- (added) libc/src/stdbit/stdc_first_leading_one_ui.h (+18)
- (added) libc/src/stdbit/stdc_first_leading_one_ul.cpp (+20)
- (added) libc/src/stdbit/stdc_first_leading_one_ul.h (+18)
- (added) libc/src/stdbit/stdc_first_leading_one_ull.cpp (+21)
- (added) libc/src/stdbit/stdc_first_leading_one_ull.h (+18)
- (added) libc/src/stdbit/stdc_first_leading_one_us.cpp (+21)
- (added) libc/src/stdbit/stdc_first_leading_one_us.h (+18)
- (added) libc/src/stdbit/stdc_first_trailing_zero_uc.cpp (+21)
- (added) libc/src/stdbit/stdc_first_trailing_zero_uc.h (+18)
- (added) libc/src/stdbit/stdc_first_trailing_zero_ui.cpp (+20)
- (added) libc/src/stdbit/stdc_first_trailing_zero_ui.h (+18)
- (added) libc/src/stdbit/stdc_first_trailing_zero_ul.cpp (+21)
- (added) libc/src/stdbit/stdc_first_trailing_zero_ul.h (+18)
- (added) libc/src/stdbit/stdc_first_trailing_zero_ull.cpp (+21)
- (added) libc/src/stdbit/stdc_first_trailing_zero_ull.h (+18)
- (added) libc/src/stdbit/stdc_first_trailing_zero_us.cpp (+21)
- (added) libc/src/stdbit/stdc_first_trailing_zero_us.h (+18)
- (modified) libc/test/include/stdbit_test.cpp (+30)
- (modified) libc/test/src/__support/CPP/bit_test.cpp (+13)
- (modified) libc/test/src/stdbit/CMakeLists.txt (+2)
- (added) libc/test/src/stdbit/stdc_first_leading_one_uc_test.cpp (+21)
- (added) libc/test/src/stdbit/stdc_first_leading_one_ui_test.cpp (+21)
- (added) libc/test/src/stdbit/stdc_first_leading_one_ul_test.cpp (+21)
- (added) libc/test/src/stdbit/stdc_first_leading_one_ull_test.cpp (+21)
- (added) libc/test/src/stdbit/stdc_first_leading_one_us_test.cpp (+21)
- (added) libc/test/src/stdbit/stdc_first_trailing_zero_uc_test.cpp (+20)
- (added) libc/test/src/stdbit/stdc_first_trailing_zero_ui_test.cpp (+20)
- (added) libc/test/src/stdbit/stdc_first_trailing_zero_ul_test.cpp (+20)
- (added) libc/test/src/stdbit/stdc_first_trailing_zero_ull_test.cpp (+20)
- (added) libc/test/src/stdbit/stdc_first_trailing_zero_us_test.cpp (+20)
``````````diff
diff --git a/libc/config/linux/x86_64/entrypoints.txt b/libc/config/linux/x86_64/entrypoints.txt
index 75e39ae51fdb06..d53b225e4d87e2 100644
--- a/libc/config/linux/x86_64/entrypoints.txt
+++ b/libc/config/linux/x86_64/entrypoints.txt
@@ -117,6 +117,16 @@ set(TARGET_LIBC_ENTRYPOINTS
libc.src.stdbit.stdc_first_leading_zero_ui
libc.src.stdbit.stdc_first_leading_zero_ul
libc.src.stdbit.stdc_first_leading_zero_ull
+ libc.src.stdbit.stdc_first_leading_one_uc
+ libc.src.stdbit.stdc_first_leading_one_us
+ libc.src.stdbit.stdc_first_leading_one_ui
+ libc.src.stdbit.stdc_first_leading_one_ul
+ libc.src.stdbit.stdc_first_leading_one_ull
+ libc.src.stdbit.stdc_first_trailing_zero_uc
+ libc.src.stdbit.stdc_first_trailing_zero_us
+ libc.src.stdbit.stdc_first_trailing_zero_ui
+ libc.src.stdbit.stdc_first_trailing_zero_ul
+ libc.src.stdbit.stdc_first_trailing_zero_ull
# stdlib.h entrypoints
libc.src.stdlib.abs
diff --git a/libc/docs/stdbit.rst b/libc/docs/stdbit.rst
index 4f242d21f8b842..790a747baaa2da 100644
--- a/libc/docs/stdbit.rst
+++ b/libc/docs/stdbit.rst
@@ -41,31 +41,31 @@ stdc_leading_ones_us |check|
stdc_leading_ones_ui |check|
stdc_leading_ones_ul |check|
stdc_leading_ones_ull |check|
-stdc_trailing_zeros_uc
-stdc_trailing_zeros_us
-stdc_trailing_zeros_ui
-stdc_trailing_zeros_ul
-stdc_trailing_zeros_ull
-stdc_trailing_ones_uc
-stdc_trailing_ones_us
-stdc_trailing_ones_ui
-stdc_trailing_ones_ul
-stdc_trailing_ones_ull
-stdc_first_leading_zero_uc
-stdc_first_leading_zero_us
-stdc_first_leading_zero_ui
-stdc_first_leading_zero_ul
-stdc_first_leading_zero_ull
-stdc_first_leading_one_uc
-stdc_first_leading_one_us
-stdc_first_leading_one_ui
-stdc_first_leading_one_ul
-stdc_first_leading_one_ull
-stdc_first_trailing_zero_uc
-stdc_first_trailing_zero_us
-stdc_first_trailing_zero_ui
-stdc_first_trailing_zero_ul
-stdc_first_trailing_zero_ull
+stdc_trailing_zeros_uc |check|
+stdc_trailing_zeros_us |check|
+stdc_trailing_zeros_ui |check|
+stdc_trailing_zeros_ul |check|
+stdc_trailing_zeros_ull |check|
+stdc_trailing_ones_uc |check|
+stdc_trailing_ones_us |check|
+stdc_trailing_ones_ui |check|
+stdc_trailing_ones_ul |check|
+stdc_trailing_ones_ull |check|
+stdc_first_leading_zero_uc |check|
+stdc_first_leading_zero_us |check|
+stdc_first_leading_zero_ui |check|
+stdc_first_leading_zero_ul |check|
+stdc_first_leading_zero_ull |check|
+stdc_first_leading_one_uc |check|
+stdc_first_leading_one_us |check|
+stdc_first_leading_one_ui |check|
+stdc_first_leading_one_ul |check|
+stdc_first_leading_one_ull |check|
+stdc_first_trailing_zero_uc |check|
+stdc_first_trailing_zero_us |check|
+stdc_first_trailing_zero_ui |check|
+stdc_first_trailing_zero_ul |check|
+stdc_first_trailing_zero_ull |check|
stdc_first_trailing_one_uc
stdc_first_trailing_one_us
stdc_first_trailing_one_ui
@@ -116,11 +116,11 @@ __STDC_ENDIAN_BIG__
__STDC_ENDIAN_NATIVE__
stdc_leading_zeros |check|
stdc_leading_ones |check|
-stdc_trailing_zeros
-stdc_trailing_ones
-stdc_first_leading_zero
-stdc_first_leading_one
-stdc_first_trailing_zero
+stdc_trailing_zeros |check|
+stdc_trailing_ones |check|
+stdc_first_leading_zero |check|
+stdc_first_leading_one |check|
+stdc_first_trailing_zero |check|
stdc_first_trailing_one
stdc_count_zeros
stdc_count_ones
diff --git a/libc/include/llvm-libc-macros/stdbit-macros.h b/libc/include/llvm-libc-macros/stdbit-macros.h
index 693a45e63419ff..19b800f342e8ff 100644
--- a/libc/include/llvm-libc-macros/stdbit-macros.h
+++ b/libc/include/llvm-libc-macros/stdbit-macros.h
@@ -86,6 +86,36 @@ inline unsigned stdc_first_leading_zero(unsigned long x) {
inline unsigned stdc_first_leading_zero(unsigned long long x) {
return stdc_first_leading_zero_ull(x);
}
+inline unsigned stdc_first_leading_one(unsigned char x) {
+ return stdc_first_leading_one_uc(x);
+}
+inline unsigned stdc_first_leading_one(unsigned short x) {
+ return stdc_first_leading_one_us(x);
+}
+inline unsigned stdc_first_leading_one(unsigned x) {
+ return stdc_first_leading_one_ui(x);
+}
+inline unsigned stdc_first_leading_one(unsigned long x) {
+ return stdc_first_leading_one_ul(x);
+}
+inline unsigned stdc_first_leading_one(unsigned long long x) {
+ return stdc_first_leading_one_ull(x);
+}
+inline unsigned stdc_first_trailing_zero(unsigned char x) {
+ return stdc_first_trailing_zero_uc(x);
+}
+inline unsigned stdc_first_trailing_zero(unsigned short x) {
+ return stdc_first_trailing_zero_us(x);
+}
+inline unsigned stdc_first_trailing_zero(unsigned x) {
+ return stdc_first_trailing_zero_ui(x);
+}
+inline unsigned stdc_first_trailing_zero(unsigned long x) {
+ return stdc_first_trailing_zero_ul(x);
+}
+inline unsigned stdc_first_trailing_zero(unsigned long long x) {
+ return stdc_first_trailing_zero_ull(x);
+}
#else
#define stdc_leading_zeros(x) \
_Generic((x), \
@@ -122,6 +152,20 @@ inline unsigned stdc_first_leading_zero(unsigned long long x) {
unsigned: stdc_first_leading_zero_ui, \
unsigned long: stdc_first_leading_zero_ul, \
unsigned long long: stdc_first_leading_zero_ull)(x)
+#define stdc_first_leading_one(x) \
+ _Generic((x), \
+ unsigned char: stdc_first_leading_one_uc, \
+ unsigned short: stdc_first_leading_one_us, \
+ unsigned: stdc_first_leading_one_ui, \
+ unsigned long: stdc_first_leading_one_ul, \
+ unsigned long long: stdc_first_leading_one_ull)(x)
+#define stdc_first_trailing_zero(x) \
+ _Generic((x), \
+ unsigned char: stdc_first_trailing_zero_uc, \
+ unsigned short: stdc_first_trailing_zero_us, \
+ unsigned: stdc_first_trailing_zero_ui, \
+ unsigned long: stdc_first_trailing_zero_ul, \
+ unsigned long long: stdc_first_trailing_zero_ull)(x)
#endif // __cplusplus
#endif // __LLVM_LIBC_MACROS_STDBIT_MACROS_H
diff --git a/libc/spec/stdc.td b/libc/spec/stdc.td
index 1720a4a3c3aaf9..b97e90d1a8ae34 100644
--- a/libc/spec/stdc.td
+++ b/libc/spec/stdc.td
@@ -781,7 +781,9 @@ def StdC : StandardSpec<"stdc"> {
Macro<"stdc_leading_ones">,
Macro<"stdc_trailing_zeros">,
Macro<"stdc_trailing_ones">,
- Macro<"stdc_first_leading_zero">
+ Macro<"stdc_first_leading_zero">,
+ Macro<"stdc_first_leading_one">,
+ Macro<"stdc_first_trailing_zero">
], // Macros
[], // Types
[], // Enumerations
@@ -810,7 +812,17 @@ def StdC : StandardSpec<"stdc"> {
FunctionSpec<"stdc_first_leading_zero_us", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedShortType>]>,
FunctionSpec<"stdc_first_leading_zero_ui", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedIntType>]>,
FunctionSpec<"stdc_first_leading_zero_ul", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongType>]>,
- FunctionSpec<"stdc_first_leading_zero_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>
+ FunctionSpec<"stdc_first_leading_zero_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>,
+ FunctionSpec<"stdc_first_leading_one_uc", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedCharType>]>,
+ FunctionSpec<"stdc_first_leading_one_us", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedShortType>]>,
+ FunctionSpec<"stdc_first_leading_one_ui", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedIntType>]>,
+ FunctionSpec<"stdc_first_leading_one_ul", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongType>]>,
+ FunctionSpec<"stdc_first_leading_one_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>,
+ FunctionSpec<"stdc_first_trailing_zero_uc", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedCharType>]>,
+ FunctionSpec<"stdc_first_trailing_zero_us", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedShortType>]>,
+ FunctionSpec<"stdc_first_trailing_zero_ui", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedIntType>]>,
+ FunctionSpec<"stdc_first_trailing_zero_ul", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongType>]>,
+ FunctionSpec<"stdc_first_trailing_zero_ull", RetValSpec<UnsignedIntType>, [ArgSpec<UnsignedLongLongType>]>,
] // Functions
>;
diff --git a/libc/src/__support/CPP/bit.h b/libc/src/__support/CPP/bit.h
index 392fbe248138ae..596b1fb530bf93 100644
--- a/libc/src/__support/CPP/bit.h
+++ b/libc/src/__support/CPP/bit.h
@@ -268,6 +268,65 @@ SPECIALIZE_FLZ(first_leading_zero, unsigned long long, __builtin_clzll)
#undef SPECIALIZE_FLZ
+#define SPECIALIZE_FLO(NAME, TYPE, BUILTIN) \
+ template <> [[nodiscard]] LIBC_INLINE constexpr int NAME<TYPE>(TYPE value) { \
+ static_assert(cpp::is_unsigned_v<TYPE>); \
+ return value == static_cast<TYPE>(0) \
+ ? 0 \
+ : BUILTIN(static_cast<TYPE>(value)) + 1; \
+ }
+
+template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
+[[nodiscard]] LIBC_INLINE constexpr int first_leading_one(T value) {
+ return value == static_cast<T>(0) ? 0
+ : countl_zero<T>(static_cast<T>(value)) + 1;
+}
+
+#if LIBC_HAS_BUILTIN(__builtin_clzs)
+SPECIALIZE_FLO(first_leading_one, unsigned short, __builtin_clzs)
+#endif
+#if LIBC_HAS_BUILTIN(__builtin_clz)
+SPECIALIZE_FLO(first_leading_one, unsigned int, __builtin_clz)
+#endif
+#if LIBC_HAS_BUILTIN(__builtin_clzl)
+SPECIALIZE_FLO(first_leading_one, unsigned long, __builtin_clzl)
+#endif
+#if LIBC_HAS_BUILTIN(__builtin_clzll)
+SPECIALIZE_FLO(first_leading_one, unsigned long long, __builtin_clzll)
+#endif
+
+#undef SPECIALIZE_FLO
+
+#define SPECIALIZE_FTZ(NAME, TYPE, BUILTIN) \
+ template <> [[nodiscard]] LIBC_INLINE constexpr int NAME<TYPE>(TYPE value) { \
+ static_assert(cpp::is_unsigned_v<TYPE>); \
+ return value == cpp::numeric_limits<TYPE>::max() \
+ ? 0 \
+ : BUILTIN(static_cast<TYPE>(~value)) + 1; \
+ }
+
+template <typename T, typename = cpp::enable_if_t<cpp::is_unsigned_v<T>>>
+[[nodiscard]] LIBC_INLINE constexpr int first_trailing_zero(T value) {
+ return value == cpp::numeric_limits<T>::max()
+ ? 0
+ : countr_zero(static_cast<T>(~value)) + 1;
+}
+
+#if LIBC_HAS_BUILTIN(__builtin_clzs)
+SPECIALIZE_FTZ(first_trailing_zero, unsigned short, __builtin_ctzs)
+#endif
+#if LIBC_HAS_BUILTIN(__builtin_clz)
+SPECIALIZE_FTZ(first_trailing_zero, unsigned int, __builtin_ctz)
+#endif
+#if LIBC_HAS_BUILTIN(__builtin_clzl)
+SPECIALIZE_FTZ(first_trailing_zero, unsigned long, __builtin_ctzl)
+#endif
+#if LIBC_HAS_BUILTIN(__builtin_clzll)
+SPECIALIZE_FTZ(first_trailing_zero, unsigned long long, __builtin_ctzll)
+#endif
+
+#undef SPECIALIZE_FTZ
+
} // namespace LIBC_NAMESPACE::cpp
#endif // LLVM_LIBC_SRC___SUPPORT_CPP_BIT_H
diff --git a/libc/src/stdbit/CMakeLists.txt b/libc/src/stdbit/CMakeLists.txt
index 65d5f344307475..fa68d4a90dbb7e 100644
--- a/libc/src/stdbit/CMakeLists.txt
+++ b/libc/src/stdbit/CMakeLists.txt
@@ -4,6 +4,8 @@ set(prefixes
trailing_zeros
trailing_ones
first_leading_zero
+ first_leading_one
+ first_trailing_zero
)
set(suffixes c s i l ll)
foreach(prefix IN LISTS prefixes)
diff --git a/libc/src/stdbit/stdc_first_leading_one_uc.cpp b/libc/src/stdbit/stdc_first_leading_one_uc.cpp
new file mode 100644
index 00000000000000..02871595fdb6b8
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_uc.cpp
@@ -0,0 +1,20 @@
+//===-- Implementation of stdc_first_leading_one_uc -----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdbit/stdc_first_leading_one_uc.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_one_uc, (unsigned char value)) {
+ return static_cast<unsigned>(cpp::first_leading_one(value));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdbit/stdc_first_leading_one_uc.h b/libc/src/stdbit/stdc_first_leading_one_uc.h
new file mode 100644
index 00000000000000..58892c3f0ff298
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_uc.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for stdc_first_leading_one_uc -----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UC_H
+#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UC_H
+
+namespace LIBC_NAMESPACE {
+
+unsigned stdc_first_leading_one_uc(unsigned char value);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UC_H
diff --git a/libc/src/stdbit/stdc_first_leading_one_ui.cpp b/libc/src/stdbit/stdc_first_leading_one_ui.cpp
new file mode 100644
index 00000000000000..a6c7ef5a833914
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ui.cpp
@@ -0,0 +1,20 @@
+//===-- Implementation of stdc_first_leading_one_ui -----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdbit/stdc_first_leading_one_ui.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_one_ui, (unsigned value)) {
+ return static_cast<unsigned>(cpp::first_leading_one(value));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdbit/stdc_first_leading_one_ui.h b/libc/src/stdbit/stdc_first_leading_one_ui.h
new file mode 100644
index 00000000000000..613adf4e1ff762
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ui.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for stdc_first_leading_one_ui -----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UI_H
+#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UI_H
+
+namespace LIBC_NAMESPACE {
+
+unsigned stdc_first_leading_one_ui(unsigned value);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UI_H
diff --git a/libc/src/stdbit/stdc_first_leading_one_ul.cpp b/libc/src/stdbit/stdc_first_leading_one_ul.cpp
new file mode 100644
index 00000000000000..d1bcab5dda02a9
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ul.cpp
@@ -0,0 +1,20 @@
+//===-- Implementation of stdc_first_leading_one_ul -----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdbit/stdc_first_leading_one_ul.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_one_ul, (unsigned long value)) {
+ return static_cast<unsigned>(cpp::first_leading_one(value));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdbit/stdc_first_leading_one_ul.h b/libc/src/stdbit/stdc_first_leading_one_ul.h
new file mode 100644
index 00000000000000..47c179f3fbacd1
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ul.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for stdc_first_leading_one_ul -----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UL_H
+#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UL_H
+
+namespace LIBC_NAMESPACE {
+
+unsigned stdc_first_leading_one_ul(unsigned long value);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_UL_H
diff --git a/libc/src/stdbit/stdc_first_leading_one_ull.cpp b/libc/src/stdbit/stdc_first_leading_one_ull.cpp
new file mode 100644
index 00000000000000..7be8f1051ec231
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ull.cpp
@@ -0,0 +1,21 @@
+//===-- Implementation of stdc_first_leading_one_ull ----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdbit/stdc_first_leading_one_ull.h"
+
+#include "src/__support/CPP/bit.h"
+#include "src/__support/common.h"
+
+namespace LIBC_NAMESPACE {
+
+LLVM_LIBC_FUNCTION(unsigned, stdc_first_leading_one_ull,
+ (unsigned long long value)) {
+ return static_cast<unsigned>(cpp::first_leading_one(value));
+}
+
+} // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdbit/stdc_first_leading_one_ull.h b/libc/src/stdbit/stdc_first_leading_one_ull.h
new file mode 100644
index 00000000000000..344d03f7100f47
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_ull.h
@@ -0,0 +1,18 @@
+//===-- Implementation header for stdc_first_leading_one_ull ----*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_ULL_H
+#define LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_ULL_H
+
+namespace LIBC_NAMESPACE {
+
+unsigned stdc_first_leading_one_ull(unsigned long long value);
+
+} // namespace LIBC_NAMESPACE
+
+#endif // LLVM_LIBC_SRC_STDBIT_STDC_FIRST_LEADING_ONE_ULL_H
diff --git a/libc/src/stdbit/stdc_first_leading_one_us.cpp b/libc/src/stdbit/stdc_first_leading_one_us.cpp
new file mode 100644
index 00000000000000..7a4c7e673f367f
--- /dev/null
+++ b/libc/src/stdbit/stdc_first_leading_one_us.cpp
@@ -0,0 +1,21 @@
+//===-- Implementation of stdc_first_leading_one_us -----------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#in...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/81526
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